We propose to examine cellular mechanisms in atherogenesis, emphasizing the role of cell surface charge in the uptake of plasma proteins, the influence of hemodynamic shear strees in the initiation, augmentation and localization of atherosclerosis, monocyte-lipoprotein interactions with reference to arterial cellular lipid accumulation, lipase activity and SMC proliferation, factor influencing monocyte-macrophase recruitment to the arterial wall, and finally, the biosynthesis and regulation of lipoprotein lipase, an important enzyme in the catabolism of traiglyceride-rich lipoproteins. In PROJECT A the influence of cationic ligands including cationized ferritin and PDGF on receptor-mediated, adsorptive and bulk phase endocytosis will be studied, with reference both to ligand charge and charge density, enzymatic modifications to cell surface associated anionic proteins, and the function of the cytoskeleton. PROJECT B will study endothelial responses to hemodynamic shear stress in vitro using a direct visualization parellel plate channel flow viscometer, and in vivo using models of aortic coarctation and bypass, with emphasis on cellular denudation, geometry, orientation, endocytosis, substrate and membrane lipid composition. PROJECT C examines the influence of monocyte activiation on lipoprotein binding, internalization, and lipid accumulation, the production of lipoprotein lipase, alterations to lipoprotein structure and composition, and on monocyte production of SMC mitogen. PROJECT D will examine arterial monocyte-macrophage recruitment with reference to monocyte-cellular attachment, the influence of lipid augmentation or depletion on monocyte-cellular attachment, the influence of lipid augmentation or depletion on monocyte chemotaxis, the production and characterization of arterial SMC-derived chemo-attractant activity, and the evolution, identification, and quantitation of monocyte derived macrophages in vascular and non-vascular tissues. Markers will be Fc and C3b receptors, NSE, and monoclonal antibodies. PROJECT E will study the biosynthesis of lipoprotein lipase, using as a model cultured differentiating pre-adipocytes, with emphasis on post-translational modification, glycosylation, regulation, adipocyte glycoprotein synthesis, enzyme purification and immunochemical localization. Core laboratories support cell culture, monocyte isolation by elutriation, macrophage culture, lipoprotein isolation purification and characterization of monocyte activation, electron microscopy, morphometry and biometry.